117 research outputs found
Interlayer exchange coupling in (Ga,Mn)As based multilayers
Exhibiting antiferromagnetic interlayer coupling in dilute magnetic
semiconductor multilayers is essential for the realisation of
magnetoresistances analogous to giant magnetoresistance in metallic multilayer
structures. In this work we use a mean-field theory of carrier induced
ferromagnetism to explore possible (Ga,Mn)As based multilayer structures that
might yield antiferromagnetic coupling.Comment: 4 pages, 2 figures. To be published in physica status solidi c as the
proceedings of the PASPS IV conferenc
Thermal equilibrium noise with 1/f spectrum from frequency independent dielectric losses in barrium strontium titanate
We investigated the dielectric losses of doped and undoped BaSrTiO3 (BST) from thermal noise measurements. The results are compared to impedance measurements. The value for the frequency independent loss angle is about tg d = 2Ă—10-2 in the range 10
Families of explicitly isogenous Jacobians of variable-separated curves
We construct six infinite series of families of pairs of curves (X,Y) of
arbitrarily high genus, defined over number fields, together with an explicit
isogeny from the Jacobian of X to the Jacobian of Y splitting multiplication by
2, 3, or 4. For each family, we compute the isomorphism type of the isogeny
kernel and the dimension of the image of the family in the appropriate moduli
space. The families are derived from Cassou--Nogu\`es and Couveignes' explicit
classification of pairs (f,g) of polynomials such that f(x_1) - g(x_2) is
reducible
LCA of perennial crops: implications of modeling choices through two contrasted case studies
International audienceAs highlighted in several recent reviews, there is a need to harmonize the way LCA of perennial crops is conducted (Bessou et al. 2013; Cerutti et al. 2013). In most published LCA on perennial crops, the agricultural production is based on data sets for just one productive year. This may be misleading since performances and impacts of the system may greatly vary year by year and the evolution of the stand over the cycle induces specific mechanisms (nutrient re-mobilization, yield alternating, resistance etc.) that must be included. Without a proper mechanistic model, the only way to account for such phenomena is to wider the data sets to at least account for each stage of the stand development and, if possible, all years of the crop cycle. Three modeling choices for the perennial crop cycle were tested in parallel in two contrasted LCA case studies: oil palm fruits from Indonesia, and small citrus from Morocco. Modeling choices tested were: i) a chronological modeling over the complete crop cycle of orchards (Bessou et al. 2013), ii) a three years average from the productive phase and iii) a selection of different single years from the productive phase. In both case studies, the system boundary included all processes from the seed production until the harvested fruits at farm-gate. The functional unit was 1 kg of fresh fruits. The chosen approach to model the perennial cycle influences the final results and deserves specific attention
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